title: Critical role of CFTR-dependent lipid rafts in cigarette smoke-induced lung epithelial injury.
abstract: Apoptosis of lung epithelial and endothelial cells by exposure to cigarette smoke (CS) severely damages the lung tissue, leading to the pathogenesis of emphysema, but the underlying mechanisms are poorly understood. We have recently established a direct correlation between decreased lipid raft CFTR expression and emphysema progression through increased ceramide accumulation. In the present work, we investigated the role of membrane CFTR in regulating apoptosis and autophagy responses to CS exposure. We report a constitutive and CS-induced increase in the number of TUNEL-positive apoptotic cells in Cftr(-/-) murine lungs compared with Cftr(+/+) murine lungs that also correlated with a concurrent increase in the expression of ceramide, NF-κB, CD95/Fas, lipid raft proteins, and zonula occludens (ZO)-1/2 (P < 0.001). We also verified that stable wild-type CFTR expression in CFBE41o(-) cells controls constitutively elevated caspase-3/7 activity (-1.6-fold, P < 0.001). Our data suggest that membrane CFTR regulates ceramide-enriched lipid raft signaling platforms required for the induction of Fas-mediated apoptotic signaling. In addition, lack of membrane CFTR also modulates autophagy, as demonstrated by the significant increase in constitutive (P < 0.001) and CSE-induced (P < 0.005) perinuclear accumulation of green fluorescent protein-microtubule-associated protein 1 light chain-3 (LC3) in the absence of membrane CFTR (CFBE41o(-) cells). The significant constitutive and CS-induced increase (P < 0.05) in p62 and LC3β expression in CFTR-deficient cells and mice corroborates these findings and suggest a defective autophagy response in the absence of membrane CFTR. Our data demonstrate the critical role of membrane-localized CFTR in regulating apoptotic and autophagic responses in CS-induced lung injury that may be involved in the pathogenesis of severe emphysema.
authors.affiliation: Department of Pediatric Respiratory Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Manish
authors.initials: M
authors.lastname: Bodas
authors.forename: Taehong
authors.initials: T
authors.lastname: Min
authors.forename: Neeraj
authors.initials: N
authors.lastname: Vij
mesh_terms: D000818:Animals; D017209:Apoptosis; D001343:Autophagy; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D002478:Cells, Cultured; D002518:Ceramides / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism*; D053222:Fas Ligand Protein / Q000378:metabolism; D005434:Flow Cytometry; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D020287:In Situ Nick-End Labeling; D055370:Lung Injury / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D021962:Membrane Microdomains / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D018181:Mice, Inbred CFTR; D018345:Mice, Knockout; D016328:NF-kappa B / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D012907:Smoking / Q000009:adverse effects*; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein
chemical_list: D002518:Ceramides; D053222:Fas Ligand Protein; D008565:Membrane Proteins; D016328:NF-kappa B; D010750:Phosphoproteins; C569042:TJP1 protein, human; C569046:TJP2 protein, human; C569043:Tjp1 protein, mouse; C569047:Tjp2 protein, mouse; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein; C485184:enhanced green fluorescent protein; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D049452:Green Fluorescent Proteins; D053148:Caspase 3; D053179:Caspase 7